most enterprise site don;t use 1TB size disk, if you want performance
you go spindles, there might be 8 disks (number pulled from the air -

based on raid6 + spares) behind 1TB

And if you want disk space and are serving across a 1Gbit ethernet link,
you don't give a damn about spindles and go for cheap abundant storage,
which means SATA.
Not everyone is running a database server. Some people just have files.
Raid5/6 of a few SATA drives can easily saturate 1Gbit. And for a very
small fraction of the cost of SAS drives.

1GBit is satturated by a single good disk already. 1GBit is a joke for
fast storage.

Erm, not on anything other than a sequential read (and even then, I've
never seen a single disk that would actually sustain that across it's
whole capacity).

Even raid-5s of significant numbers of disks aren't enormously fast,
especially under multiple access. hdparm informs me that the SATA 28+2
spare raid-5 I have will read 170M a second. That would rapidly diminish
under any sort of load.

The only thing we've found that'll stand up to real multiuser load (like
a mail spool) is raid-10, and enough spindles.

We're beginning to see the requirement for 10GE on busy machines.
--
ian